The True Wood Cost of One Kilogram of Charcoal: From Green Gathered Wood to Saleable Product

Laboratory and kiln yields are usually quoted per kilogram of oven-dry wood, but nobody gathers oven-dry wood: wood is cut green, carried with its bark on, and loses pieces to drying and handling before it reaches a kiln. This study, which is simulated, not measured, follows that chain with stated assumptions — green moisture of 0.45 by weight (wet basis, central case), a bark fraction of 0.10 of dry mass yielding no saleable charcoal, a drying loss of 0.04, and a handling loss of 0.03 — and applies the saleable oven-dry yields of 0.192, 0.2848, and 0.3534 kg/kg for earth-mound, brick, and metal retort kilns. The green wood that must be cut and carried per kilogram of charcoal sold is then 11.299 kg for the earth mound, 7.617 kg for the brick kiln, and 6.139 kg for the retort, against oven-dry figures of 5.208, 3.511, and 2.830 kg. The gap ratio is 2.169 at the central moisture for every method: the field cost is more than twice the figure a dry-basis yield suggests. Across the stated moisture range the green cost spans 9.561 to 13.81 kg for the earth mound, 6.446 to 9.31 kg for the brick kiln, and 5.194 to 7.503 kg for the retort. Planning, quotas, and prices set from dry-basis yields alone will understate the wood that must actually be cut by roughly half.